Re: [PATCH] USB: gadget: f_fs: Use memdup_user() as a cleanup

[Greg KH <greg@kroah.com>]

On Fri, Mar 19, 2021 at 05:15:46PM +0800, Jay Fang wrote:
> From: Zihao Tang <tangzihao1@hisilicon.com>
> 
> Fix coccicheck warning which recommends to use memdup_user():
> 
> drivers/usb/gadget/function/f_fs.c:3829:8-15: WARNING opportunity for memdup_user
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Zihao Tang <tangzihao1@hisilicon.com>
> Signed-off-by: Jay Fang <f.fangjian@huawei.com>
> ---
>  drivers/usb/gadget/function/f_fs.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index 801a8b6..2f904f0 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -3826,14 +3826,7 @@ static char *ffs_prepare_buffer(const char __user *buf, size_t len)
>  	if (!len)
>  		return NULL;
>  
> -	data = kmalloc(len, GFP_KERNEL);
> -	if (!data)
> -		return ERR_PTR(-ENOMEM);
> -
> -	if (copy_from_user(data, buf, len)) {
> -		kfree(data);
> -		return ERR_PTR(-EFAULT);
> -	}
> +	data = memdup_user(buf, len);

You forgot the error checking :(